I can't help but wonder weather or not it would be possible to protect the unvented opti from moisture by this method; maybe not so much as to turn it into a vented opti, but at least to keep moisture from getting in when it's raining.
Please correct me if I am wrong, but I believe there are 3 (?) "weep" holes on the bottom of the unit, which cause the major problem by sucking moisture into it when the opti becomes hot and then cools because of the vacuum created by that effect?
First, is there any real need for these holes? Would the opti last longer if they were filled with JB Weld?
Secondly, if at least one of the holes (as long as the other two were plugged) were connected to a small diameter rubber hose that did nothing more than snake to somewhere warm and dry, would that be a benefit as well?
If any of this were doable wouldn't it be a quick and easy semi-fix to a POA problem?
If this is off the wall, I apologize I am not a rocket scientist, just very curious!

 

The early opti's were vented (three holes at the bottom), and really aren't that sucepable to moisture (via the three holes.

The problem with the early opti's is:
1. They are not positively vented, and therefore ozone builds up inside, which makes the metal parts corrode. The opti is a separate assy from the engine, and doesn't see any engine vacuum. Engines with a conventional distributor have positive venting via the distributor driveshaft.
2. The optical pickup is mounted on the botom, so any corriosion, dirt, moisture will accumulate on the pickup.

The later opti's have a positive venting system to eliminate the ozone buildup, however they dont remove accumulated moisture as well. The single "drain" port is not at the very bottom of the opti, and water will collect. Look at pictures of a later opti disassembled, and you'll see a rust line in the bottom of the opti.

The later opti's also have the pickup mounted on the top, to help keep it clean.

All opti's are succeptable from moisture via the gasket/seal between the cap and housing. When I replaced mine, I ran a bead of RTV around the outside if this joint. Otherwise, moisture that condenses on the outside of the opti will migrate into the opti.

All opti's are very succeptable to shorting/crossfiring due to moisture on the exterior of the opti, either as a result of water splashing or condensation.

Keep a can of STP Wire Dryer or Contact Cleaner in your trunk, and spray the opti, coil, and coil wire evrye 6 months, or if you suspect moisture. My original opti lasted 160K, even after numerous water soakings and "dead Opti" symptoms.

 

Thanks for the info, That was the best discription of the problem i've heard.
Would you suggest putting some kind of sealant on the cap also(around each connection) where the plug wires connect once I install it?